I dry hop after fermentation in the same carboy that I fermented in. I've yet to suffer autolysis, or even have an off-flavor from it. It's been my experience that 6 to 8 weeks on the lees in a clean sanitized carboy that never gets opened (or only opened for a minute while you sanitize the opening and dump in hops) isn't likely to be an infection vector, and you're not likely to get autolyzed yeast either so long as you keep your temperatures within about the same conditions you'd ferment in or perhaps slightly lower temperatures.